The sense latch circuitry of the above referred to copending application and of the pending application of Robert J. Lodi, Ser. No. 736,551 filed Oct. 28, 1976, now abandoned, operate in response to the differential inputs from MNOS FET memory cells. The differential inputs are cross coupled in a bistable latching arrangement such that the latch produces outputs corresponding to binary data stored in the memory cells.
Due to the inherent nature of the MNOS FET, the reading of binary data stored in MNOS FET memory cells is dependent on the retention time of the individual MNOS FETs which comprise each cell. The retention time is further dependent on the magnitude and duration of the write signal, the read cycle time and the amount of read disturb, which all affect the number of reads that are possible before the separation between the MNOS FET's threshold levels become indistinguishable. It is therefore desirable that the sense latch, which senses the threshold separation, be sensitive enough to detect the separation for as many read operations as possible before the separation becomes indistinguishable.